/**
  * Author: Mei
  * Date: 2020-11-21 9:07
  * Description: 
  *
  */
#include <iostream>
#include <vector>
#include <algorithm>
#include <memory>
#include <utility>
#include <functional>
#include <numeric>

using namespace std;

template<typename T, int b = 20>
T fun(T x) {
    //++b; //非类型参数是常量，不能修改
    return x + b;
};

int main() {
    int a = 10;
    cout << fun < int > (a) << endl;

    return 0;
}